The prevalence of all investigated mental disorders in prisoners is higher than general population comparisons. Prisoners are also at increased risk of mortality, suicide, self-harm, violence and victimization. These facts alone make mental health among prisoners a crucial issue for any prison service. In addition, some mental conditions are strongly associated with early onset of anti-social development. Treatment of such conditions, for example substance abuse disorders, ADHD and psychosis, has shown significant reductions on risk for recidivism. Methods for screening, assessment and treatment for these various conditions exist, but can still be a challenge for prison agencies to implement and maintain. There is also much that can be done to improve release measures and collaboration with other agencies or NGOs to ensure continuous treatment and follow up.